JP B 56-37414 discloses a control apparatus of a throttle valve which calculates a target opening of the throttle valve on the basis of engine speed and required engine torque, and controls so that a real throttle valve opening becomes a target opening.
Further, JP A 7-332136 discloses a throttle valve control apparatus of an internal combustion engine, which is provided with a throttle valve driving means for driving a throttle valve inserted in an engine intake system, a target opening setting means for setting a target opening of the throttle valve, a throttle valve opening detecting means for detecting an opening of the throttle valve, and an opening-closing control means computing a feedback control quantity including a proportional part using a difference between a target opening set by the target opening setting means and a detection opening detected by the throttle valve opening detecting means, driving the throttle driving means on the basis of the calculation result and effecting feedback control so as to cause the throttle valve to approach the target opening, wherein a proportional part gain changing means is provided in which a gain relating to the proportional part is made larger as the above-mentioned difference becomes smaller.
Still further, JP A 8-144820 discloses a throttle valve control apparatus of an internal combustion engine, which obtains a target opening of a throttle valve provided in an intake passage of the internal combustion engine mounted on a vehicle on the basis of required engine torque calculated according to engine speed and various conditions of the vehicle and electrically controls so that a real throttle valve opening becomes the above-mentioned target opening, and which is characterized by comprising an intake pressure detecting means for detecting intake pressure in the intake passage, a target intake pressure computing means for computing a target intake pressure in the intake passage according to the engine speed and required engine torque, and a correcting means for comparing the above-mentioned target intake pressure and a detection intake pressure and correcting the above-mentioned target opening according to the result.
Those official publications disclose the proportional part gain changing means or means for improving the response of the throttle valve by correcting an target opening calculated by an engine control unit itself.
However in the case of these methods, since motor driving duty is calculated using a certain constant fixed for operation of the throttle valve, the overall response is improved but an influence on the response of the throttle valve due to external or secular change or manufacturing variations in the products has not been improved as yet.